The present invention pertains to digital display devices such as liquid crystal display panels and related interface circuitry that may be used to display images. The present invention is related more particularly to the presentation of two or more independent images on a plurality of digital display devices using one set of control signals.
Digital display devices such as liquid crystal display (LCD) panels, thin-film-transistor (TFT) panels and plasma panels are used in various applications such as personal computer systems and micro-processor based industrial controllers to present visual images. Digital display devices are being incorporated into additional types of applications as manufacturing costs of the display devices continue to decrease. One relatively new application is the so called electronic book in which one or more digital display devices are arranged to display text and graphics in a manner that resembles pages in a conventional book.
Electronic circuitry sometimes referred to as a video adapter or a display controller provides an interface between a digital display device and various other components that provide the digital information representing an image to be displayed. In typical applications, a display controller receives a set of input digital signals that represent components of the image to be displayed and, in response, generates a set of output digital signals that cause an attached digital display device to present the desired image. The output digital signals are generated by the display controller to meet the input signal requirements of the display device.
There is a growing demand for devices and systems that use multiple display devices to present independent images. Two display devices may be used in personal computer systems to display independent images such as different areas of a virtual desktop, the visual presentation of two different computer applications that are executing simultaneously, or two independent visual presentations of a single computer application. For example, numerical data in an electronic spreadsheet may be presented by one display device and a corresponding graphical display of the numerical information may be presented by a second display device. In the electronic book application mentioned above, two display devices may be used to present independent images that represent different pages in a book.
Two ways are known for providing an interface between two display devices and the other components that provide digital information representing two independent images. One way uses separate display controllers for each display device. This approach allows essentially any type of display device to be used for either image but it is often not an attractive solution because of the space and power required by the circuitry of the two independent display controllers, and for the space required for all of the connectors needed to connect the circuits to multi-conductor cables. Two independent controllers may also be incompatible with one another, causing the apparatus in which the controllers are used to malfunction.
A second way to interface two display devices is disclosed in U.S. Pat. Nos. 5,488,385 and 5,694,141, which are incorporated herein by reference. According to this approach, interfaces for two display devices are provided by one display controller having some common circuitry shared by both display devices and some distinct circuitry for each display device. The use of common circuitry reduces the space and power required to provide the interfaces for two display devices but the use of distinct circuitry for each display device does not reduce the space required for circuit connectors.
There are a number of applications such as the electronic book application mentioned above in which two identical, or at least very similar, display devices are used to present independent images. In such applications, the flexibility provided by distinct circuitry is not needed and the space and power required by this circuitry is a disadvantage.
It is an object of the present invention to provide an efficient interface for presenting independent images by two or more digital display devices operating according to the same or similar input signal requirements and to reduce implementation costs by reducing the space required by the circuitry and the number of connectors required to connect to the circuitry. This object is achieved by the present invention as described below and as set forth in the claims.
According to one aspect of the present invention, an apparatus includes input-interface circuitry that receives data signals representing a plurality of independent images and associated control signals; memory; a memory controller in communication with the input-interface circuitry and the memory to control writing information into and reading information from the memory, wherein the information corresponds to the data signals representing the plurality of independent images; one or more display-pipeline circuits in communication with the memory to receive the information representing the plurality of independent images; and output terminals in communication with the one or more display-pipeline circuits, wherein the output terminals provide a first clock signal and a plurality of output-data signals conveying interleaved components of the plurality of independent images, and wherein the output-data signals conveying components for a first of the plurality of independent images are aligned with the first clock signal.
According to a second aspect of the present invention, a system includes processor circuitry that generates data signals representing a plurality of independent images and associated control signals; input-interface circuitry in communication with the processor circuitry to receive the data signals and the associated control signals; memory; memory controller in communication with the input-interface circuitry and the memory to control writing information into and reading information from the memory, wherein the information corresponds to the data signals representing the plurality of independent images; one or more display-pipeline circuits in communication with the memory to receive the information representing the plurality of independent images; output terminals in communication with the one or more display-pipeline circuits, wherein the output terminals provide a first clock signal and a plurality of output-data signals conveying interleaved components of the plurality of independent images, and wherein the output-data signals conveying components for a first of the plurality of independent images are aligned with the first clock signal; and a plurality of display devices in communication with the output terminals, wherein a respective display device presents a respective one of the plurality of independent images.
According to a third aspect of the present invention, a method for transmitting signals representing two or more independent images for presentation by two or more display devices generates a sequence of first signal components representing components of a first image, wherein a respective first signal component represents a respective component of the first image; generates a sequence of second signal components representing components of a second image that is independent of the first image, wherein a respective second signal component represents a respective component of the second image; and transmits along a data-signal channel the first signal components interleaved with the second signal components and transmitting along a control-signal channel a first clock signal, wherein a respective first signal component is aligned with a respective cycle of the first clock signal.
According to a fourth aspect of the present invention, an apparatus for transmitting signals representing two or more independent images for presentation by two or more display devices includes means for generating a sequence of first signal components representing components of a first image, wherein a respective first signal component represents a respective component of the first image; means for generating a sequence of second signal components representing components of a second image that is independent of the first image, wherein a respective second signal component represents a respective component of the second image; and means for transmitting along a data-signal channel the first signal components interleaved with the second signal components and transmitting along a control-signal channel a first clock signal, wherein a respective first signal component is aligned with a respective cycle of the first clock signal.
According to a fifth aspect of the present invention, each of a plurality of display devices includes a plurality of image-data signal input connections; a plurality of display-control signal input connections; a clock signal input connection; control circuitry having inputs in communication with the image-data signal input connections, the display-control signal input connections and the clock signal input connection; and a display screen in communication with outputs of the control circuitry; wherein respective image-data signal input connections for the plurality display devices are coupled together and respective display-control signal input connections for the plurality display devices are coupled together, and respective clock signal input connections for the plurality of display devices are coupled to sources of respective clock signals.
According to a sixth aspect of the present invention, an electrical socket includes a plurality of electrical connections used to convey signals representing two or more independent images for presentation by two or more display devices, wherein the electrical connections include a first clock-signal connection that conveys a first clock signal; and a plurality of data-signal connections that convey a sequence of first signal components interleaved with a sequence of second signal components, wherein a respective first signal component represents a respective component of a first image, a respective second signal component represents a respective component of a second image that is independent of the first image, and a respective first signal component is aligned with a respective cycle of the first clock signal.